基于AMPK/SREBP-1c分子通路的山楂原花青素调控脂质代谢机制

Hawthorn Procyanidins Regulate Lipid Metabolism through the AMPK/SREBP-1c Signaling Pathway

目的:探讨山楂原花青素(hawthorn procyanidins,HPC)调节腺苷酸激活蛋白激酶/固醇调节元件结合蛋白(AMP-activated protein kinase/sterol regulatory element binding protein-1c,AMPK/SREBP-1c)信号通路对脂质代谢的影响及其机制。方法:采用随机数字表法将大鼠分为空白对照组(blank control group,BCG),高脂血症模型组(hyperlipidemia model group,HMG),HPC低、中、高剂量组(HPC-low-, medium-and high-dose groups,HPC-LDG、HPC-MDG、HPC-HDG),非诺贝特阳性对照组(fenofibrate positive control group,FPG),每组10只。按试剂盒方法检测大鼠血清和肝匀浆中甘油三酯(triglyceride,TG)、总胆固醇(total cholesterol,TC)、低密度脂蛋白胆固醇(lowdensitylipoproteincholesterol,LDL-C)和高密度脂蛋白胆固醇(highdensity lipoproteincholesterol,HDL-C)浓度;苏木精-伊红(hematoxylineosin,HE)染色观察各组大鼠肝脏组织病理学变化;实时定量聚合酶链式反应检测各组大鼠肝脏中AMPK、SREBP-1c、甘油-3-磷酸酰基转移酶(glycerol-3-phosphate acyltransferase-1,GPAT1)、乙酰辅酶羧化酶(acetyl CoA carboxylase,ACC)、脂肪酸合成酶(fatty acid synthese,FAS)、肉毒碱棕榈酰基转移酶(carnitine palmitoyltransterase-1,CPT1)和过氧化物酶体增殖物激活受体γ辅助激活因子1α(peroxisome proliferator activated receptor γ coactivator-1α,PGC-1α)mRNA表达水平;蛋白质免疫印迹法(Western blot)检测各组大鼠肝脏中p-AMPK、SREBP-1c、GPAT1、ACC、FAS、CPT1和PGC-1α蛋白表达水平。结果:造模7周后,与BCG比较,HMG大鼠体质量、肝质量和肝脏指数均显著或极显著升高(P<0.05、P<0.01)。与HMG比较,HPC-HDG和FPG大鼠血清和肝匀浆TG、TC和LDL-C浓度极显著下降,HDL-C浓度极显著升高(P<0.01),且HPC对大鼠血清和肝匀浆中脂质浓度影响有剂量依赖性。采用各剂量HPC预防性干预后,随HPC剂量增加,大鼠肝细胞脂肪变性逐渐改善。与HMG比较,HPC-HDG和FPG大鼠肝脏AMPK mRNA和p-AMPK蛋白相对表达量均极显著上升(P<0.01),大鼠肝脏SREBP-1c、GPAT1、ACC、FAS mRNA和蛋白相对表达量均极显著下降(P<0.01),大鼠肝脏CPT1、PGC-1α mRNA和蛋白相对表达量均极显著升高(P<0.01)。结论:HPC可以改善高脂血症大鼠脂质代谢,其作用机制可能与AMPK/SREBP-1c分子信号通路有关。

Objective:To investigate the effect of hawthorn procyanidins(HPC)on lipid metabolism and its mechanism by regulating the AMP-activated protein kinase/sterol regulatory element binding protein-1c(AMPK/SREBP-1c)signaling pathway.Methods:Sixty rats were randomly divided into six groups(n=10)blank control(BC),hyperlipidemia model(HM),low-,medium-,and high-dose HPC(HPC-LD,HPC-MD,and HPC-HD)and fenofibrate positive control(FP).The contents of triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) in the serum and liver homogenate were measured by commercial kits. Hematoxylin eosin (HE) staining was used to observe hepatic histopathological changes. The mRNA expression levels of AMPK, SREBP-1c, glycerol-3-phosphate acyltransferase-1 (GPAT1), acetyl CoA carboxylase (ACC), fatty acid synthase (FAS), carnitine palmitoyltransterase-1 (CPT1) and peroxisome proliferator activated receptor γ coactivator-1α (PGC-1α) in the liver were measured by quantitative real-time polymerase chain reaction (PCR). Western blotting was used to detect the protein expression of p-AMPK, SREBP-1c, GPAT1, ACC, FAS, CPT1 and PGC-1α in the liver. Results: After seven weeks of feeding on a high-fat diet, body mass, liver mass and liver index significantly increased compared with the control group fed on a basal diet (P < 0.05 or < 0.01). Compared with the HM group, the contents of TG, TC and LDL-C in serum and liver homogenate in the HPC-HD and FP groups significantly decreased, and the content of HDL-C significantly increased (P < 0.01);the effect of HPC on lipid content in serum and liver homogenate was dose-dependent. After prophylactic intervention with HPC, the steatosis of hepatocytes was gradually improved with an increase in the dosage of HPC. Compared with the HM group, the AMPK mRNA expression and p-AMPK protein expression in liver tissues in the HPC-HD and FP groups significantly increased (P < 0.01), and the mRNA and protein expression of SREBP-1c, GPAT1, ACC and FAS significantly decreased (P < 0.01), and the mRNA and protein expression of CPT1 and PGC-1α significantly increased in the liver (P < 0.01). Conclusion: HPC can effectively improve lipid metabolism in hyperlipidemic rats, which may be related to the regulation of the AMPK/SREBP-1c signaling pathway.